1. Technical Field
The present invention relates to a vehicle headlamp which is configured to form light distribution patterns by light radiation from lamp units which employ semiconductor light-emitting elements as light sources.
2. Related Art
As described in JP-A-2003-123517, a related art vehicle lamp including a plurality of lamp units that employ semiconductor light emitting elements as light sources has been conventionally known.
A related art vehicle headlamp is generally configured to allow switching between a low-beam and a high-beam. A low-beam light distribution pattern having sharp cut-off lines at an upper end portion can be formed when a so-called projector-type lamp unit is employed as the lamp unit, and a light-shielding member is disposed at a rear focal point of the projection lens. In a projector-type lamp unit, light from a light source is reflected to a position closer to the optical axis of the projection lens by a reflector and is substantially converged in the vicinity of a rear focal point of the projector lens. The light-shielding member shields a part of light reflected from the reflector.
However, when a lamp unit is provided with only such a light-shielding member, the lamp unit becomes a low-beam-only lamp unit that forms only a low-beam light distribution pattern. As a result, and another lamp unit for forming a high-beam light distribution pattern is required.
When a semiconductor light-emitting element is employed as a light source of a lamp unit, disposing a plurality of lamp units is preferable to ensure a desired brightness. However, when a lamp unit for low-beam and a lamp unit for high-beam are configured independently, there arises a related art problem that a number of lamp units required for a vehicle headlamp becomes considerably large.